1. Field of the Invention
The invention relates to a method of accumulating located states of appliances in a distributed computer system in which a plurality of appliances are mutually connected through a network and to an apparatus using such a method. More particularly, the invention relates to household appliances and facility appliances which are connected to a home network.
2. Description of the Related Art
In recent years, the number of kinds and the number of appliances connected to a home network system have been increased. There are cases where the appliances are installed at positions where the resident (user) is not aware of, the user himself directly connects the appliances to the network, and the like. It is becoming difficult to grasp which kinds of appliances are installed at which places. If the installing positions are found, for example, in the case where a sensor fails, it is possible to rapidly and easily find a place of the failed sensor among a number of sensors installed in a house. If the appliances can be classified every room from the installing positions, for instance, it is possible to utilize the system for an energy saving control such that the presence or absence of a person is detected by a human body sensor and a set temperature of an air conditioner which is performing the cooling operation is raised or illumination is turned off in a room where there is no person.
Hitherto, in the home network system, since only the limited appliances are connected to the network and the number, the kinds, and the installing places of the connected appliances are known upon construction, which appliances have been installed at which places in the house can be easily grasped without an aid of a computer system technique. In recent years, however, as the number of appliances installed in the house increases gradually, a technique for managing the installing positions is necessary. With such a background, how to set the installing positions of the appliances, such as on which floor, at which places, and in which room in the house they are set, is important. The following methods are used as methods of setting them by a computer system.    (1) In the home network system, installing positions information of the appliances which are installed in the house is set into each appliance by the construction trader or the user or set into an appliance for concentratedly managing those information. As setting methods, there are a method of setting them in a hardware manner like a dip switch, a method of setting them into software, and the like. However, according to all of those methods, they have to be manually set each time.    (2) In a radio network which is used in the home network system, for example, communication among the appliances is made via an access point which is installed every room and communication between the appliances located in the different rooms is made via a plurality of access points. Therefore, by examining via which access point the appliance is communicating, the installing position can be easily judged, regarding that the installing position of each appliance has been set in the same room as that of the access point.    (3) The method of calculating a distance between the appliances from a time difference that is caused until a response is made after a transmission message is transmitted has been disclosed in JP-A-5-48623.
However, according to the technique described in the above method (1), it is very troublesome for the user to execute the setting by himself. That is, it is needless to say that it is troublesome to set the installing position into each appliance. With respect to the technique described in the above method (2), as a medium of the network which is used in the home network system, it is not limited to a radio wave but an indoor wire, infrared rays, a telephone line, a twisted pair line, or the like is often used. There is, further, a case of forming one system by combining those plurality of media. It is insufficient according to the installing position obtaining method of appliances mainly using access points of the radio network. Even if appliances connected to different media exist, respectively, in the same room, it is difficult to recognize them. According to the example of the above method (3), although a length of transmission path of a physical network can be recognized, since it is not a physical straight line distance between the appliances, even if the transmission path length is known, it is difficult to discriminate an actual positional relation of the appliances. For example, in a detached house in which the appliances are connected by the indoor wire network, in most of the cases, the appliances in a plurality of rooms are connected by a single indoor wire in most of the cases. Even if the above technique is used, the room where the appliances have been installed cannot be discriminated on a room unit basis. According to such a technique, a network construction by a single transmission medium is considered as a prerequisite, and it cannot be used in a network construction environment comprising a plurality of transmission media.
That is, there is a problem such that it is difficult to automatically discriminate the installing positions of each appliance and obtain the position information irrespective of the network construction.
It is more difficult to discriminate the installing positions of each appliance by a remote control via the wide area network.